Today is the 40th anniversary of the first flight of the Boeing 737, the best-selling commercial jetliner in aviation history. On April 9, 1967, Brien Wygle (photo left), Boeing's assistant director of flight operations, and co-pilot Lew Wallick (photo right) landed a Boeing 737-100 after a historic 2.5 hour flight from Boeing Field to Paine Field in Washington state. "I hate to quit", Wygle said after landing, "the airplane is a delight to fly". Today, more than 541 operators fly Boeing 737s into 1200 cities in 190 countries. With more than 4100 airplanes in service, the 737 represents more than 25% of the total worldwide fleet of large commercial jets. On average, there are about 1250 737s in the air at all times, and one takes off or lands every 4.6 seconds. Since commercial revenue service began in 1968, Boeing 737s have carried more than 12 billion passengers more than 75 billion miles, a distance equivalent to 403 round trips from the Earth to the sun.
The Boeing Company developed the 737-100 in order to compete with Sud Aviation's SE 210 Caravelle, the British Aircraft Corporation's (BAC) 111, and the Douglass DC-9. These earlier entrants into the short-range, small-capacity jetliner market threatened to squeeze Boeing out of a growing segment in commercial aviation. In 1958, a full three years after France's Sud Aviation had produced the world's first short-to-medium range jet airliner, Boeing announced design-study plans for a "a twin engine feeder airliner to complete the family of Boeing passenger jets". In November of 1964, Boeing named Jack Steiner (photo left), the aerospace engineer who was known as the "father of the 727", as chief engineer for the Boeing 737-100. With rival aircraft already into flight certification, Steiner accelerated the 737's development time by using 60% of the parts from the Boeing 727, including its doors, cockpit layout and avionics. By widening the 737's cross-section, Steiner gave the 737-100 six-abreast seating, one more than either the DC-9 or BAC-111. The Boeing 737's spacious interior also enabled the aircraft to carry standard-sized cargo containers on its main deck, and to use standard cabin fittings such as galleys from the 727.
As part of his design team, Jack Steiner recruited Joseph Sutter (photo left), the son of a Slovenian immigrant and the future father of the Boeing 747. While working at his desk one day, Sutter took some scissors and cut up a drawing of the initial design of the 737. As he moved the engines around, Sutter positioned the cutouts tight under the wings instead of away from the wings on struts. Sutter's vision, which he later described as "a sudden flash of excitement", offered several advantages over the T-tail design used on airplanes such as the 727. For starters, aircraft with wing-mounted engines reduced interference drag and featured a better of center-of-gravity. They also provided easier engine access for maintenance crews and required less pipework for fuels and bleeds. Sutter's theory that the weight of the engines would provide bending relief from the lift of the wings was a bit of stretch, however. When a set of wings failed in static tests at 95% of maximum load, the 737-100's wings had to be completely redesigned. "The final wing", one aviation historian has written, was "a work of art" that provided "both good short field performance and economy at altitude".
Just two years after the launch of the Boeing 737-100 project, Brien Wygle and Lew Wallick completed their historic flight across Washington state. Although the first Boeing 737s had problems with their thrust reversers and landing gear, the Seattle-based aerospace company completed flight-testing full-speed ahead, clocking almost 50 hours of flight time in the first month. Less than a year later, the first 737s entered service in February 1969 with Lufthansa, the German airliner. Although only 30 737-100s were ever produced, the introduction of the longer 737-200 and the improved 737-200 Advanced would carry the Boeing Company to new heights in the years to come.